Device for cutting screw-threads.



T. SHEHAN.

DEVICE FOR CUTTING SCREWTHREADS.

APPLICATION FIL ED DEC. l 5, 1913 Patented Mar. 28, 1916.

2 SHEETS-SHEET1.

Iw'enzor:

J MW

THE COLUMBIA PLANOGIAP" 00-, IIAIHINGTON, D. C-

THOMAS SHEHAN, F CLEVELAND, OHIO;-

DEVICE lOR CUTTING SCREW-THREADS.

Specification of Letters Patent.

Application filed December 15, 1913. Serial No. 806,743. I

To all whom it may concern:

Be it known that I, THOMAS SI-IEHAN, a

citizen of the United States of America,

residing at Cleveland, in the county of Cuyahoga and State of Ohio, haveinvent- 1 ed certain new and useful Improvements in Devices for CuttingScrew-Threads; and I hereby'declare the following to be a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it pertains to make and use the same.

This invention relates to improvements in devices for cuttingscrew-threads, and more especially to a collapsible tap or deviceadapted for cutting internal screw-threads and comprising a cutter-headwhich has a centrally located bore extending endwise or longitudinallyof the cutter-head and is provided in its forward portion with radiallyarranged guideways which are spaced circumferentially of said bore andengaged by cutters adapted for cutting screW threads.

One object of this invention is to provide improved simple, durable andreliable means for shifting or adjusting the cutters simultaneously.

Another object is to provide improved means whereby the cutters, uponhaving completed their cutting operation on the oo ect to bescre\vthreaded, are automatically and simultaneously and correspondinglywithdrawn from the work.

Another object is to provide means whereby the cutters, when they are inan operative position for cutting a screw-thread, can be readily andsimultaneously and correspondingly readjusted for making a deeper orshallower cut.

Another object is to render the cutters readily replaceable by othercutters.

With these objects in view, and to the end of attaining any otheradvantagehereinafter appearing, this invention consists in certainfeatures of construction, and combinations and arrangement of parts,hereinafter described, pointed out in the claims, and illustrated in theaccompanying drawings.

In said drawings, Figure 1 is a side view of a portion of a latheprovided with my improved device for cutting screw-threads, and aportien of the object or work which is to be internally screw-threadedby said device is shown in section to disclose its hollow character.Fig. 2 is a section, in

Patented Dial". as, 1916.

detail, on line 22, Fig. 1, looking in the 7 direction indicated by thearrow. Fig. 3 is a forward end view'of my improved device for cuttingscrew-threads. Fig. 4 is a vertical section on line 4- 1, Fig. 1,looking rearwardly. Fig. 5 is a section on line 55, Fig. 4, lookingoutwardly. Fig. 6 isa horizontal section on line 66, Fig. 1, lookingdownwardly. Fig. 7 is a vertical section on line 7-7, Fig. 1, lookingrear.-

wardly. Fig. 8 is a vertical section on line 88, Fig. 6, lookingforwardly. Fig. 9 is a section on line. 9-9, Fig. 3, looking in thedirection indicated by the arrow. Fig. 10 is a verticalsectiononline-10l0, Fig. 1, looking forwardly. Fig. 11 is a section on line11l1, Fig. 10, looking in'the. direction indicated by the arrow. Fig. 1is drawn on a smaller scale than the remaining figures which are drawnon the same scale.

. Referring to Fig. 1 of the drawings, A 7

indicates the bed of a lathe which is provided with an upright standarda from which my improved collapsible'tap or de-' vice for cuttingscrew-threads is supported. Said device for cutting screw-threadscomprises a stock B and a cutter-head C, and D indicates the cutters ofthe cutter-head. A work-feeding head E is shown engaging a slideway 15formed in the bed A, and said slideway is arranged as required to enablesaid head to be moved toward and from the tap or device for cuttingscrew-threads. G indicates a horizontally arranged spindle which hasbearing in the head E and is parallel with the slideway 15 and providedwith two collars 16 and 17 :arranged to prevent endwise movement of thespindle in opposite directions independently of said head. Said spindleis suitably rotated, and the head E is shifted endwise of the slideway15 in any approvedImanner so as to shift the spindle endwise during therotation of the jecting arm 5 which is shown in Fig. 1 as extending intoand supported from the standard a to which sa1d arm is secured by aset-screw 18. The stock B (see Fig. 6) is provided centrally with ahorizontally arranged bore 20 which extends endwise of and through thestock, and said here is enlarged diametrically, as at 21, at the forwardend of the stock.

The cutter-head C is arranged next forward of and supported from thestock B. Preferably the cutter-head C (see Figs. 6 and 7) is secured tothe stockB removably by suitably applied bolts or screws 22 which extendhorizontally through the stock and are screwed into the cutter-head and(see Figs. 1 and 6) have heads 23 abutting against the exterior of thestock. The forward portion of the cutter-head C substantiallycorresponds in diameter with the arm 7) of the stock B, and the rearend-portion of the cute ter-head is larger diametrically than. theforward portion of the cutter-head and sub stantially correspondsdiametrically with the forward end of the stock. The forward portion ofthe cutter-head C is provided (see Figs. 1, 10 and 11) with four slotsor guideways 24 which are spaced equidistantly circumferentially of achamber 25 arranged centrally of said portion of the Each guideway 24-extends radially of the cutter-head C from the chamber 25 to theexterior of the cutter-head and is engaged by ,a cutter D. Thecutter-head is provided centrally (see Figs. 6 and 9) with a bore 26which extends endwise of the central portion of the cutter-head and isseparated from the chamber 25 by a suitably formed partition 27, andsaid bore is therefore out of communication with said chamber. The bore26 is arranged in line endwise with the bore 20, and a substantiallyhorizontally arranged tube 28 is shown extending from within the bore 20at a point rearwardly of the dia metrical enlargement 21 of thelast-mentioned bore forwardly into the bore 26. The cutter-head is alsoprovided between adjacent cutters (see Figs. land 9) with a hole .orpassageway 29 which extends from the bore 26 to a point at the-exteriorof the guideway -containing vportion of the cutterhead. The bore 20,tube 28 and bore 26 form. a passageway for, receiving oil or lubricantand conducting said lubricant to the passageways 29, and each passageway29 is employed in conducting lubricant to theexterior of thecutter-carrying portion of the cutter-head. Each cutter D has its teethformed at its outer end in any approved manner and is adjustable orshiftable radially {of the cutter-head. Each guideway 24 has itsrearwardly facing forward wall formed by a circular plate H whichoverlaps each cutter G and is secured in place removably by suitablyapplied screws h.

' with a recess cutter-head.

Each cutter D (see FigsulO and 11) is provided in and centrally of oneside thereof 30 which is preferably 511". ranged between said side and apoint centrally between said side and the opposite side of the cutterand. extends horizontally through the cutter and is engaged by the crank32 of a crankshaft I which is ar-. ranged horizontally and endwise ofthe cutter-head and has bearing rearward of said crank in thecutter-head and forward of the crank in the plate H which is rigid withthe cutter-head. Said crank extends therefore endwise of and throughsaid recess which is 7 parallel with said shaft. Each shaft I has itsportion which has bearing in the plate H smaller diametrically than andarranged in line endwise with its portion which is arranged rearward ofthe cranks 32. Each shaft I has its portion which has bearing in thecutter-head rearward of its crankaslarge in diameter as the forwardportion or, remainder of the shaft so as to require the formation of thehole 33 which is formed in the cutter-head for the reception of saidportion of said shaft and large enough to permit the passage of thecrank 32 of the shaft endwise through said hole during the assemblage ofthe parts,-and said crank is in contact with opposite side walls of theengaging recess 30 so as to cause the cutter thus operatively connectedwith said crank to be actuated inwardly or outwardly according as theshaft isrotated in the one or the other direction. To permit thereduction to a minimum of the depth of the recess 30 in each cutter andthereby avoid unduly weakening the cutter, said cutter and thecrank-shaft operatively connected with said cutter have such relativearangement that the cutter is arranged in the main at one side of theaxis of the shaft, and the cutterhead (see Fig. 10) is recessed or cutaway,

as at 31, at one of the walls of the slideway' engaged by said cutterand opposite the recess 32 in each cutter and from end toend of saidrecess, as shown in dotted lines, Fig. 11,

to avoid interference with the operationand location of the crankengaging said ;recess and to permit replacement of said cutter upon theremoval of the pla'teI-I.

The bore 26 in the cutter-head connects at its rear end (see Fig. 6),with a circular'a chamber 3 formed in the rear end-portion. andextending to'the rear-extremity of the cutter-head and around the tube28 and arranged concentrically relative'to said tube. The chamber 34:isnot only large enough diametrically to receive an internal gear J whichhas bearing inthe cutter-head at the surrounding wall of saidchamber-and extends circumferentially of and is concentric relative tothe tube 28,but to permit exten-' sion of the shafts I to said chamberand the formation on the rear end of each shaft I of a spur-gear 35which meshes with the internal gear J. That is, each shaft I isoperatively provided at its rear end with a spurgear 35 which isarranged within the forward portion of the chamber 34. The gear J has arearwardly projecting annular flange 36 which is arranged concentricallyrelative to the tube 28 and provided externally with a handle 37extending to and beyond the exterior of the cutter head and employedinrotating said gear. The handle 37 is shown projecting outwardlythrough a slot38 formed in the cutter-head at the surrounding wall ofthe chamber 34, which slot extends from saidchamber outwardly to theexterior of the cutter-head and far enough circumferentially of saidchamber to ace commodate the location and operation of said handle..Obviously the gears .35 are spaced from -and circumferentlally of apoint centrally of the cutter-head, and said gears correspond so thatall of the shafts I are rotated simultaneously and correspondinglyduring the actuation of the gear J.

As the cutters D are shown in their outer and operative position readyfor operation on and internally of the tubular or hollow member or workto which is fed to and along and screw-threaded internally by thecutters, the handle 37 is shown as having been shifted in the directionindicated by the arrow 39, Figs. 3 and 7, and as having thereby efiectedthe rotation of the shafts I in said direction as required to effectmovement of the cutters from their inner or inoperative position (notshown) into'their outer and operative position illustrated, and it willbe observed that when the cutters are in their operative position therotation of the shafts I in the opposite direction actuates the cuttersinwardly and thereby withdraws the cutters from their operative posiisarranged a coiled spring K which is coiled around the tube 28 and isattached at one end, as at 0, to the stock and at its other end, as at4-2, to the flange 36 of the gear J.

' By the construction hereinbefore described it will be observed thatthe crankshafts I, and consequently the cutters D, are operativelyconnected with the gear J, and said shafts are rotated in the onedirection or the other according as said gear is rotated in the one orthe other direction.

In the outer or operative position of the cutters D the spring K isunder such tension as may be required to rotate the gear J and shafts Iin the direction required to' effect a shifting of the cutters inwardlyand thereby withdraw the cutters from said position when said gear andsaid shafts are rendered free, in said position of the cutters,

n ithin the diametrical enlargement 21 of the bore 20 in the stock B(see Figs. 6 and 7) to rotate in said direction. Locking means wherebythe internal gear J and the shafts I are locked against rotation in salddirection by the springK are provided, and said locking means, as willhereinafter appear,

are operative in the operative position of the cutters but adapted to berendered inop erative by. an arm Z of an endwise shiftable rod L which(see Figs. 1, 3, 4, 5 and 7) is axis of said gear, and engages a hole asformed in and centrally of and extending endwise of and through acorrespondingly arranged circular block or member N which supports saidpin and is seated at its circumferential surfacein the stock and adjusteable about its own axis. The pin-supporting member N is parallel withthe pin M and consequently parallel with the axis of the gear J. The pinM is supported therefore independently of the gear J, and said pin isprovided at its forward end with a head m. In the operative position ofthe cutters D the pin -M is in its forward and operative position inwhich the head m of the" pin is spaced forwardly'from the forward, endof the pin supportin'g member N so as (see Figs. 1, 2, 5and shiftablepin M,

roe

to permit rearward movement of saidpin against the action of a coiledspring P which is coiled around said pin between the forward end of thepin-supporting member N and the head m. The spring P extends intoarecess formed in the rear end of the head m and acts to retain the pinM in its forward and operative position shown in Fig. 6. The stock B ischambered interiorly, as at d6, to accommodate thelocation and operationof the pin'M, pin-supporting member N and arm [of the rod L.

The v gear J is provided at the rear'or outer end of its flange 36 (seeFigs. 4, 5 and 7) with a shoulder J preferablyformed by i one end faceof a curved'plate or member 47 which is secured to said flange in anyapproved manner and'arranged concentrically relative to the axis of thegear, and said shoulder faces in the direction inwhich i said gear isrotated in shifting the cutters from an operative into an inoperativeposition and in the operatlve position of the cutters abuts against amember 48 of the head'm of the pin M. That is, the pin M has a member 48which in the operative po sition of the cutters is engaged by theshoulder J of the gear J when the pin is in its forward and operativeposition so as to lock said gear and the shafts Iagainst rotation in thedirection in which said gear is rotated inshifting the cutters from anoperative into an inoperative position, and of course said pin isrendered inoperative by shifting the pin fa r enough endwise in therequired direction. The member 48 of the pin M is arrangel at the faceand projects forwardly of the head m of said pin, and said member 48 isspaced from the axis of the pin. Of course the cutters D during theshifting of the same from an inoperative position into an operativeposition move against the action of the spring K which acts therefore toretain the cutters in their inoperative position. The stock B (see Figs.4, 5 and 7) is, of course, recessed or cut away whenever required, as at50, to accommodate the location of the member 47 of the gear J and thearm Z of the rod L. By the construction hereinbefore described it isobvious that all that is required to actuate the cutters D by the springK from an operative to an inoperative position is to render the pin Minoperative by shifting it far enough rearwardly to disengage the member48 of said pin from the shoulder J m of the pin M (see Figs. 2, 5 and G)is provided with a rearwardly projecting member 49 which is parallel.with the axis of and projects into the pin-supporting member N which isprovided with a hole 51 loosely engaged by said member 49 and extendingbeyond the rear or free end of. said member 49 far enough to permitrearwardly endwise shifting of the pin M independently of thepin-supporting member. That is, the relative arrangement of the parts issuch that the member 4970f the pin M projects into the hole 50 in anyposition of the pin. The pin M is therefore operatively connected withthe pin-supporting member N so far as concerns readjustment of the pinabout its axis by and'simultaneously with a readjustment of thepin-supporting member about its own axis for the purpose of curatelyadjusting the cutters relative to the work to be operated on withoutinterfering with the shiftability independently of the pin-supportingmember. Preferably the member 48 of the pin M is formed by the head of ascrew which is screwed into the head m of the pin and extends endwise ofand through the lastmentioned head and beyond the rear end of saidlast-mentioned head. and the member 49 of the head m is preferablyformed by the shank of said screw.

The pin-supporting member N (see Figs. 1 and 2) is secured in thedesired adjustment about its own axis by two screws R and 1" carried bythe stock 13 and spaced circumferentially of said member and abuttingagainst shoulders 52 and. 53 formed on the pin-supporting memof the gearJ. The head.

of said pin endwise and I pin-supporting her. That is, thepin-supporting member Nis provided with two shoulders 52 and- 53 spacedcircumf rentiallyof said member and engaged by the inner ends of the 7screws R and 7* respectively, which screws are preferably screwed intothe stock "B from the exterior of the stock and some.-

what converge inwardly, and said shoulders form walls of recesses 54which are formed in the pin-supporting member N and are large enough indimensions to accommodate the location of said screws and a read ustmentof sald pin-supportlng mem- I her and the connected pin .M about theiraxes by a proper manipulation of said screws.

The stock B is apertured, as at 55, at the outer side of thepin-supporting member, N (see Figs. 1 and 2) to efiect the exposure, at

the circumference of the stock, of a portion of said pin-supportingmember, and the circumferential surface of said pin-supporting member isvisible therefore at the extenor of the stock and graduated, as at 56.

Fig. 1, to indicate the circumferential adjustment of the pin M andconsequently to indicate the adjustment of the cutters.

The arm Z of the rod L; in the forward and normal position of said rodis arranged next forward of or overlaps the faceof the head m of the pinM, so that during the shifting of said rod rearwardly said pin isactuated rearwardly to remove its member 48 -rear. wardly from theshoulder J of the gear J and thereby-render said gear and the connectedshafts I free'to be rotated bythe spring, K in the 'directionrequired towithdraw the cutters D fr'omthe work operated on by the cutters.Obviously the rod L while being against the action of therefore acts toretain said rod in its forward and normal position. The rod L: may beactuated rearwardly endwise in any approved manner, and .(as shown inFigs, 1..

3 and 5) said rod is provided at its forward shifted, rearwardlymovesthe spring P which end and externally of the cutter-head with adownwardly projecting arm 57 which is shown removably secured to saidarm by a suitably applied screw 58, and the workfeeding head E has anarm or projecting member 60 arranged to come into engagement at theproper time, during "the feed mg of the work to while said work is beingoperated on by the cutters D, with the arm 57 of the rod L and thereuponactuate said rod rearwardly to effect the actuation of thegear from saidmember of said'pin and con-.

sequently unlock the gears 35 subject to the action of the spring K andpermit the latter to rotate said gears in the direction re- ;uired toeifect the rotation of the shafts I in the direction required to shiftthe cutters into their inoperative position and thereby cause saidcutters to release the work.

To replace the cutters D by other cutters, the plate H is removed fronithe forward end of the cutter-head, whereupon the shafts I aremanipulated to permit the withdrawal.

of the cutters forwardly from the cutterhead and the application ofother cutters to said shafts.

What I claim is 1. In a device for cutting screw-threads, a cutterieadprovided with guideways which extend radially of and to the exterior ofthe cutter-head; cutters engaging the guideways, each cutter beingprovided at and centrally of one side thereof with a recess extendinghorizontally through the cutter; a plate forming the rearwardly facingwall of the aforesaid guideways and removably secured in place; acrankshaftjhaving its crank extending endwise of and through theaforesaid recess, said shaft being arranged longitudinally of thecutter-head and having bearing in the cutter-head rearward of its crankand also having bearing in the aforesaid plate and having its portionwhich has bearing in the cutter-head rearward of said crank as large indiameter as any farther forwardly arranged portion of the shaft.

2. In a device for cutting screw-threads, a cutter-head having itsforward portion provided with radially arranged spaced cutters andprovided centrally of said portion with a chamber and having guidewaysfor the cutters of the cutter-head, which guide-ways extend from saidchamber to the exterior of the cutter-head, said cutter-'headbeingprovided rearward 'of said chamber and centrally with alubricant-receiving bore which is out of communication with saidchamber, and the cutter head having passageways which extend from saidbore to the exterior of the aforesaid portion of the cutter-head.

3. In a device for cutting screw-threads, a stock provided centrallywith a horizontally arranged bore which is adapted to receive lubricantandextends endwise of the stock;

a cutter-head arranged next forward of and secured to the stock andprovided centrally ofits forward portion with a chamber and havingguideways which extend from said chamber to the exterior of thecutter-head, which cutter-head is provided with cutters engaging saidguide-ways and has a centrally located bore arranged rearwardly of andout of communication with said cham-- being provided with passagewayswhich ex-v tend from the bore in the cutter-head to the exterior of theaforesaid portion of the cutter-head, and a tube establishingcommunication between the bore in the stock and the bore in thecutter-head and arranged wholly rearward of the aforesaid passageways.

4t. In a device for cutting screw-threads, a stock; a cutter headarranged forward of and supported from the stock and provided internallywith a chamber and having guidewaysarranged forward of said chamber andextending to the exterior of the cutter-head; cutters engagingsaidguideways; an internal gear having bearing in the cutter-headcircumferentially of said chamber; spaced corresponding spur-gearsmeshing with said internal gear and operatively connected with thedifferent cutters respectively; a suitably applied spring which is undersuch tension in the operative position of the cutters as may be requiredto rotate thegears in the. direction necessary toshift the cutters froman operative into an inoperativeposit1on when said gears are renderedfree," in

the operative position of the cutters,.to rotate' in said direction, andlocking means whereby said gears are locked against rotation in saiddirection said locking means being operativein the operative position ofchamber and extending to the exterior of the cutter-head; cuttersengaging; said guideways an internal gear having bearing'in thecutter-head at the surrounding wall of said chamber; spacedcorresponding spur-gears meshing with said internal gear and operativelyconnected with the different cutters respectively; a suitably supportedcoiled spring arranged at the rear of the aforesaid chamber and attachedat one end to the stock and at its other end tothe internal gear, saidspring being under such tension in the operative position of the cuttersas maybe required to rotate the gears in the direction necessary toshift the cutters from an operative into an inoperative position whensaid gears are rendered free, in the operative position of the cutters,to rotate-in said direction, and locking means whereby said gearsarelocked against rotation in said direction, said locking means beingoperative in the operative position of-the cutters but adapted toberendered inoperative.

6. In a device for cutting screw-threads, a cutter-head provided in itsforward portion and ceiitrallv with a chamber and having guideways whichextend radiallv of and to; the exterior of the cutter-head from and arespaced circumferentially of said chamber; cutters engaging theguideways; a cut-- ter-actuating crankshaft for each cutter, whichcrank-shaft has its crank operatively connected with said cutter and issupported from the cutter-head; a suitably supported internal gearoperatively connected with the cutters and having a shoulder which facesin the direction in which said gear is rotated to shift the cutters froman operative into an inoperative position; means acting to rotate said.gear in said direction when the cutters are in an operative position,and a pin which is substantially parallel with the axis and supportedindependently of said gear and adjustable about its own axis andprovided with a member which is spaced from the axis of the pin andengaged :by the aforesaid shoulder in the operative position of thecutters, said pin and said gear being capable of being relativelypositioned in the operative position of the cutters to permit said gearto rotate in the aforesaid direction.

7. In a device for cutting screw-threads, a cutter-head provided in itsforward portion and centrally with a chamber and havingguideways whichextend radially of and to the exterior of the cuttenhead from and arespaced circumfer-entially of said chamber; cutters engaging theguideways; a cutter-actuating crankshaft for each cutter, whichcrank-shafthas its crank operatively connected with said cutter and issupported from the cutter-head; a suitably supported internal gearoperatively connected with the cutters and having a shoulder which facesin the direction'in which said gear is rotatedin shifting the cuttersfrom an operative intoan inoperative position; a spring actingto rotatesaid gear in said direction in the operative positionof the cutters, anda pin supported independently of said gear and having a member which inthe operative position of the cutters is engaged by the aforesaidshoulder when the pin is in its locking position, said pin beingshiftable in the direction required to move its said member out ofengagement with said shoulder and thereby render said gear subject tothe action of the aforesaid spring.

8.1n a devicefor cutting screw-threads, a cutter-head provided withshiftable cutters; a suitably supported-internal gear 0perativelyconnected with the cutters and having a shoulder which faces inthedirection in which said gear is rotatedto shift.

the cutters from an operative into an in operative position; meansacting in the operative position of'the cutters to rotate said gear insaiddirection'; an endwise shiftable pin which is substantially parallelwith the axis of said gear and provided at its forward end with aforwardly projectingmemher which is spaced from the axis of the pin andengaged by the aforesaid shoulder in the operative pos tion of thecutters, said pin being in its forward position in the last-mentionedposition of the cuttersg:

means acting to retain said pin in its for.- ward position and in saidposition being shiftable far enough rearwardly to disengage itsaforesaid projecting member from the aforesaid shoulder; a suitablysupported circular member surrounding and supporting said pinfsaidpin-supporting memberbeing ad ustable about its own axis, and means forsecuring SillCl pin supporting.

member in the desired adjustment, the pin being movable with thepin-supporting memberduring a readjustment of the pinsupporting memberabout its axis, and the. pin-supporting member being arranged to permitthe requisite endwise shiftability ofv the pinindependently of thepin-supporting member.

9. In a device for cuttingscrew-threads,

a stock; a cutter-head arranged forward of and supported from the stockand provided with shiftable cutters; a-suitably supported internal gearoperatively connected with the cutters and having a shoulder whichfaces: in the .directionin which said gear is rotated I to shift thcutters from an operative HIlZO an inoperative position; means acting inthe operative position of the cutters to'rotate. said gear in saiddirection; an endwiseshiftable' pin which is substantially parallel withthe axis of said gear and provided at. its forward end with. a forwardlyprojecting 7 member which is engaged by the aforesaid shoulder in theoperative position of the cutters and spaced from: the axis of the pin,.said pin being in its forward POSltlOIl: 1D

surrounding and supporting SttlClPlI1, Slldpin-supporting member havingbearing =.in the stock and being ad ustable about its own axis andhaving two shoulders spaced-.

circumferentially of'said axis, and screws screwed intothe stock andabutting against 1 said shoulders, the pin being movable with:

the pin-supporting member during the re-' about its axis.

10. In a device for cutting screw-threads, a cutter-head provided withshiftable. cutters; a suitably supported internal gear op-- ters from anoperative into an inoperative 13081131011; means acting in the operativep0" sition of the cutters to rotate said gear insaid direction; anendwise shiftable pin which is substantially: parallel with the axis-ofsaid gear andprovided at its foradjustment of the pin-supporting member.

ward end with a head having a forwardly projecting member which isengaged by the aforesaid shoulder in the operative position of thecutters and spaced from the axis of the pin, said head having arearwardly projecting member which is parallel with the pin, said pinbeing in its forward position in the last-mentioned position of thecutters; means acting to retain the pin in its forward position, and asuitably supported member surrounding and supporting said pin and spacedfar enough rearwardly from the aforesaid head in the forward position ofthe pin to permit rearward movement of the pin the extent required todisengage ative position; means acting in the operative 7 position ofthe cutters to rotate said gear in said direction; an endwise shiftablepin which is substantially parallel with the axis of said gear andprovided at its forward end with a head having a forwardly Copies ofthis patent may be obtained for five cents each, by addressing theGommissioner of Patents,

projecting member which is engaged by the aforesaid shoulder in theoperative position of the cutters and spaced from the axis of the pin,said head having a rearwardly projecting member which is arrangedparallel with the pin, said pin being in its forward position in thelast-mentioned position of the cutters; means acting to retain the pinin its forward position; a suitably supported circular membersurrounding and supporting said pin and spaced far enough rearwardlyfrom the aforesaid head in the forward position of the pin to permitrear- 4 ward movement of the pin the extentrequired to disengage theaforesaid forwardly projecting member of said head from, the aforesaidshoulder, said pin-supporting member having bearing in the stock andadjustable about its own aXis and being provided with a hole engaged bythe aforesaid rearwardly projecting member of said head, which hole isengaged by the lastmentioned projecting member in any position of thepin, and means for securing the pin-supporting member inthe desiredadjustment.

In testimony whereof, I sign the foregoing specification, in thepresence of two witnesses. V

' THOMAS SHEHAN. Witnesses l a HERBERT G. WOOD, B. C. BROWN.

Washington, D. G. I

